tter be not natives of his kingdoms,
or his vassals or subjects), to the said islands, lands, and seas
within said line, nor shall he consent nor give them aid or favor
or permit them to go there, contrary to the form and determination
of this contract. Rather he shall be obliged to forbid, suppress,
and prevent it as much as possible. Should the said emperor and
king of Castilla, personally or through an agent, send natives of
his kingdoms, or his vassals, subjects or aliens (although these
latter be not natives of his kingdoms, or his vassals or subjects),
to the said islands, lands, or seas within the said line or consent
to such a thing, giving them aid, or favor, or permitting them to
go contrary to the form and determination of this contract; and
should he not forbid, suppress, or prevent it, as much as possible,
the said agreement of _retro vedendo_ becomes null and void; and the
said King of Portugal shall no longer be obliged to receive the said
sum, nor to sell back the rights and dominion which the said emperor
and king of Castilla might have therein in any manner whatsoever,
but which he has sold, renounced and delivered to the said King
of Portugal by virtue of this contract, by this very act, the said
sale shall remain complete and valid forever, as if at first it were
made without condition and agreement to sell back. However, since
it may happen that, when the aforesaid subjects, natives, or vassals
of the said emperor and king of Castilla navigating as aforesaid in
the southern seas, should meet with winds so tempestuous or contrary
that they would be constrained by necessity to continue their course
and navigation within the said line, they shall in such case incur no
penalty whatever. On the contrary, when, in such circumstances, they
shall come to and anchor at any land included within the said line,
pertaining by virtue of this contract to the said King of Portugal,
they shall be treated by his subjects, vassals, and inhabitants of
said land as the vassals of his brother, as in the same manner the
emperor and king of Castilla would command the Portuguese subjects to
be treated who should in like manner arrive at ports in his lands of
Nueva Espana or in any other of his ports. It is understood, however,
that, when such necessity ceases, they shall immediately set sail
and return to their part of the southern seas. Should the aforesaid
subjects cross said line through ignorance, it is herein covenanted